Supporting and holding the head of a patient during craniotomy and other surgical operations in the head area are difficult tasks since the head is a spheroidal organ. Invasive operations in the head involve in many cases forceful acts like sawing the skull. Therefore, the need to firmly hold the head is very important On the other hand, there is also the need to move or rotate the head prior to or during the operation itself, so that the surgeon is able to perform the operation comfortably. The ease in moving or rotating the head in order to position it according to the surgical team needs is very important.
Some commercial surgical head supports are available and known in the art. A commercial head frame is manufactured by Mizuho Medical Co. LTD. The surgical head support, commercially called "Mizuho Radiolucent Head Frame", comprises a crown base on which articulations needed for the procedure can be fixed, and an enlarged head holder that renders rigidity to the crown. The head frame further comprises a table attachment for connecting the head holder to the operation table or the bed on which the patient lies The space around the patients head that this head frame occupies is relatively broad.
Ohio medical Instrument Company, Inc., manufactures a patented "Cranial Positioning System", which is disclosed in U.S. Pat. No. 3,836,861 filed in 1972. This invention provides a surgical head damp that includes two sections. One section carries a pair of head engaging pins. The second section can carry a single pin. The sections are connected by a disc and pawl arrangement, which permits rapid closure movement to bring the pins rapidly into contact with sides of the head. The pair of pins is mounted on a sliding arcuate bar, which is slidably mounted on the first section and movable to adjust for irregularities of the head and to insure proper direction of the pair of pins. The outer pin is carried by a threaded carrier, which is threaded to the second section and permits fine adjustment of the positioning of the pins. The carrier includes a spring, which urges the pin carrier thereby toward the head to provide resilient urging of the pins. The force of the spring can be varied to adjust the pressure of the clamp. This surgical head clamp has relatively large dimensions around the patient's head, and the multijoint arm that supports the head clamp also takes up a large space. Furthermore, in order to take up certain peculiar positions the multijoint arm might occupy even larger space around the patient's head.
Recently intraoperative imaging devices were introduced, offering on-line information to the surgical team and providing better operational conditions. Such is, for example, the compact MRI apparatus, described in U.S. Pat. No. 5,900,793 (Katznelson et al.), where the image acquiring means include a pair of small permanent magnets that are spaced so as to allow the insertion of the head of the patient in between them. The space within the magnets is very limited (usually in the order of 25-40 cm) and this greatly limits the size of a surgical head support that can be used for holding the patient's head during surgery.
Prior art and other standard head holders or clamps that engage relatively large space around the patients head do not allow the head to be positioned between the two magnets of the portable MRI. Moreover, the patient's head cannot be maneuvered easily in order to reposition the head in a better position relative to the surgeon or to additional medical devices that are sometimes needed in the course of operation.
There is a distinct need for a surgical head support that is confined to the near vicinity of the patient's head. In order to provide better operation conditions for the surgeon and a simple way to position and support the head, there is also a need for a good leverage system. The head holder itself has to match and firmly hold a patient's head also catering for abnormalities in head sizes or shape.